In this paper, we present for the first time, a classification system for naturally-occurring gas hydrate deposits existing in the permafrost and marine environment. This classification is relatively simple but highlights the salient features of a gas hydrate deposit which are important for their exploration and production such as location, porosity system, gas origin and migration path. We then show how this classification can be used to describe eight well-studied gas hydrate deposits in permafrost and marine environment. Potential implications of this classification are also discussed.
Tyagi, Anisha (California State Polytechnic University-Pomona) | Grenier, Margaret (California State Polytechnic University-Pomona) | Kreuziger, Rachel (California State Polytechnic University-Pomona) | Kays, Jacob (California State Polytechnic University-Pomona) | Polet, Jascha (California State Polytechnic University-Pomona)
The San Gabriel and San Bernardino Basins are sedimentary basins located in southern California that are surrounded by a network of faults and comprised of soft sediments. Sedimentary basins are known to amplify earthquake ground motions and increase their duration. The San Gabriel and San Bernardino Basins are densely populated areas; therefore, it is important to determine site characteristics for seismic hazard mitigation. Furthermore, if a major rupture were to occur on the Southern San Andreas Fault, the San Gabriel and San Bernardino Basins could potentially amplify the ground motion and funnel the energy from the rupture into the Los Angeles Basin (Denolle et al., 2014), acting as a waveguide. Therefore, it is important to better characterize these basins and to understand their resonance period, amplification and site response. Three seismic profiles, containing over 200 threecomponent nodes, were installed across the San Gabriel and San Bernardino Basins in the first quarter of 2017 and collected approximately one month of continuous waveform data. We apply the Horizontal-to-Vertical Spectral Ratio (HVSR) method to the ambient noise waveform data from this experiment. The resulting spectral ratio curves show clear long period peaks (between 2 and 5 seconds) that likely correspond to basin resonance and that indicate significant variation in amplification factors and resonance frequencies across both basins. Preliminary results show these long period peaks for nodes to the South of the Raymond Fault along a profile in the Western part of the San Gabriel Basin, as well as across the central part of this basin. The peak frequencies for the Western profile suggest that the basin is relatively deeper in this area. Nodes in the Southern half of the Chino Basin indicate values for peak frequencies between those measured for the San Gabriel Basin lines. Peak amplitudes vary between 2 and 4.5, which indicates potential for significant ground motion amplification.
Presentation Date: Wednesday, October 17, 2018
Start Time: 1:50:00 PM
Location: Poster Station 14
Presentation Type: Poster
Hogan, Phillip Joseph (Fugro West, Inc.) | Lane, Andrew (Woodside Energy Ltd. ) | Hooper, James (Fugro-McClelland Marine Geosciences) | Broughton, Aaron (Fugro West, Inc.) | Romans, Brian (Stanford University)
Geotechnical data, geochronologic data, and high resolution seismic data collected for Woodside's OceanWay Secure Energy LNG project allow an improved understanding of the tectonic and sedimentary processes in Santa Monica Bay and Basin, and identification of geologic hazards.
The proposed facilities are located in a deepwater basin near the collisional transform boundary of the Inner California Continental Borderland (ICB) Province with the Western Transverse Ranges (WTR) Provinces. This area is characterized by complex interactions between blind thrust faults underlying the Los Angeles Basin and strike slip faults related to the northwest motion of the Pacific Plate relative to North America. Active faults and folds crossing the proposed pipeline route present a ground rupture and deformation hazard on the continental slope.
Active sediment transport processes and high sediment accumulation rates are documented on Hueneme submarine fan in Santa Monica Basin (SMB). High-resolution seismic-reflection profiles across Ocean Drilling Program (ODP) borehole 1015 in the basin plain provide a well-dated chronostratigraphic record. Turbidity currents in Santa Monica Basin are sand-dominated, and have increased in sediment volume per event in the latest Holocene. Whilst some turbidites likely result from El Niño-Southern Oscillation (ENSO) storm events, others are believed to have been triggered by seismically-induced strong ground motions.
The potential exists for surface folding and fault rupture, seismically induced strong ground motions, and turbidity currents to affect the proposed pipeline within the lifetime of the project. These geohazards will be mitigated through appropriate analyses, risk studies, and engineering design of the OceanWay facilities, allowing safe and secure importation of natural gas to the West Coast of the USA.
Proposed LNG developments in deepwater offshore the West Coast of the United States face new challenges, both on technical issues such as facility engineering and from natural geologic processes. Many recent high-profile deepwater developments continue to encounter major geological hazards (geohazards) on an increasing scale worldwide.
Woodside Natural Gas, Inc. (Woodside) proposes to import LNG to Southern California via a Deepwater Terminal in SMB. SMB is one of several basins in the ICB, a tectonically active area along the plate boundary between the Pacific and North American Plates (Figure 1). A 56-km submarine pipeline will bring the gas ashore via a horizontal directional drill borehole at a landfall in the coastal portion of the Los Angeles Basin (Figure 2). Detailed feasibility and siting studies were performed in 2005 and 2006 to assist in the selection of the optimal location of the OceanWay Project. This paper summarizes geohazards identified during the 2006 geophysical and geotechnical surveys.
Rabinowitz, P.D. (Texas A&M University ) | Francis, T.J.G. (Texas A&M University ) | Baldauf, J.G. (Texas A&M University ) | Coyne, J.C. (Texas A&M University ) | McPherson, R.G. (Texas A&M University ) | Merrill, R.B. (Texas A&M University ) | Olivas, R.E. (Texas A&M University )
The material is subject to correction by the author. Permission to copy is restricted to an abstract of not more than 300 words.
An instrumented, tri-moor cable structure was implanted successfully using a phased implant technique in 2,900 feet of water in the Santa Monica Basin off Southern California. The experimental structure was constructed to provide a platform for evaluating cable structure design techniques and recent developments in ocean engineering technology.
The analytical model used to design the structure is described and predicted structure displacements due to two assumed current profiles are presented. Guidelines used in the mechanical and electrical design of the structure are outlined, and the subsystems and major components are described. The techniques which resulted in the successful implant are presented.
Although sufficient data are not yet available to evaluate in detail the analytical model used to design the structure, data obtained do indicate gross agreement between theory and actual performance.
All mechanical and most electrical equipment survived the implant. Although some component failures have occurred, the design philosophy has been successful in avoiding any subsystem failures.
During the past fifteen years numerous analytical models have been developed to analyze the steady-state behavior of moored cable systems. These models attempt to predict the tensions in the cables and the geometry of the moorings acted on by steady-state ocean currents. None of these models yield exact solutions because of the inexact assumptions regarding structural properties and hydrodynamic loading criteria and because of errors inherent in the computational techniques. 1 Because little experimental data exist to validate models, except those for designing very simple moors, precise validation data are needed to quantify the errors associated with the various techniques. 1 The SEACON II structure was designed and built primarily to satisfy this need for data on the steady-state response of a complex cable structure to ocean currents. An additional objective of the SEACON II project was to evaluate recent developments in ocean engineering technology while implanting and operating the cable structure.
The SEACON II structure (Figure 1) consists of a delta-shaped module tethered by three mooring legs (L1, L2, and L3) in 2,900 feet of water. Legs L1 and L2 are torque-balanced mechanical cables and L3 is a torque-balanced electromechanical (EM) cable. Each leg is 4,080 feet long. The delta module with 1,000-foot-long EM cable arms is positioned approximately 500 f be10w the surface and is buoyed at each apex by a 5½-foot-diameter spherical buoy (NBl, NB2, and NB3). The mechanical cable legs (Ll and L2) are anchored with experimental deep ocean explosive embedment anchors (AI and A2). The EM cable leg (L3) is anchored by a l2,500-pound clump anchor (A3) which contains a 10-watt radioisotope power generator (RPG). The anchors are positioned approximately 6600 feet apart. An EM wire rope crown line (CL) extends from the clump anchor to an 8-foot-diameter crown buoy (CB) 50 feet below the surface. Electronics and recording equipment is stored within a removable pressure canister in the crown buoy.
In the article, "Sailboats and Drilling Rigs" (May, 1968, JPT, Page 451), authors C. S. Hutchinson and L. K. Williams have done a splendid job in describing the agonies and conflicts of interest between the people of Corpus Christi and the objectives of the oil industry relative to the discovery and development of oil reserves in Corpus Christi Bay. Indeed, the situation that the authors portray appears virtually to be identical with the problems presently confronting the citizens of Santa Barbara, problems presently confronting the citizens of Santa Barbara, Calif., the oil industry, the State of California and the U. S. government, who own the submerged lands seaward of Santa Barbara.
The case at Santa Barbara involves lands in which the City has no interest other than that derived from ad valorem taxation, and like the submerged lands of Corpus Christi Bay, the waters near Santa Barbara are believed to overlie rich accumulations of oil and gas. Santa Barbara has been effective in obtaining State legislation that has resulted in the creation of a state sanctuary within the 3-mile limit, for 13 miles along the Santa Barbara coastline. So far, the City has been unsuccessful, however, in projecting this sanctuary seaward into Federal waters; but projecting this sanctuary seaward into Federal waters; but the outcry from the City has been sufficiently intense that certain officials including, most recently, Secretary Udall have delayed the leasing of Federal lands until a relatively popular solution is achieved.
The situation with respect to waters bounding upon the City of Los Angeles is slightly different. These submerged lands have been granted to the City of Los Angeles by legislative act and, therefore, the City has a proprietary interest to accompany its concern for the aesthetic attributes connected with drilling operations in Santa Monica Bay.
The history of what Los Angeles has accomplished in the upland portion of the city is well known. The oil industry has faced up to the challenge of drilling in an urban environment in such a way as to be compatible with residential and commercial zoning, and the pictures presented by authors Hutchinson and Williams in their presented by authors Hutchinson and Williams in their paper provide cogent testimony to the success of urban Los paper provide cogent testimony to the success of urban Los Angeles drilling operations. Without the innovations represented by the drillsites of Occidental Petroleum Corp., Standard Oil Co. of Calif., and Mobil Oil Corp's lighthouse facility at Venice Beach, oil reserves measured in hundreds of millions of barrels might well have never been opened to the drill. Under the present circumstances, both operators and townlot property owners adjacent to these facilities are pleased with the results and rewards of urban oilfield pleased with the results and rewards of urban oilfield development.
Just as the City of Corpus Christi is doing, the City of Los Angeles is grappling with the complex problems of developing oil reserves in a marine environment, where preservation of aesthetic values is uppermost in the minds preservation of aesthetic values is uppermost in the minds of everyone. We have approached our problems in two separate ways; one, from the standpoint of zoning regulations, the other to include radical changes in the design of any drilling structures that might be considered for construction in the sanctuary areas. A considerable section of our Municipal Code now is devoted to the ground rules of drilling in Santa Monica Bay. Not only have we defined the nature, scope and purpose of such regulations, but we have attempted to quantify them in a meaningful fashion by providing for the establishment of offshore oil drilling districts in which operations would be governed by stringent controls over drilling facilities. With respect to our efforts to achieve new styles in the appearance of platforms, we have on hand a report that describes the impact of the use of color and design innovations. The work done by the City's architectural contractors in this connection has stimulated further study to determine what else might be done to render offshore drilling operations compatible with a marine environment.
Authors Hutchinson and Williams state that any realistic appraisal of the future compels us to consider the social environment when it comes to drilling for oil and gas. We heartily echo this remark, in that it applies with particular aptness to the situation along coastal California. In sanctuary areas the public interest requires that drilling operations not impair aesthetic and recreational values; and if marine drilling facilities can be made more attractive to the public, enormous areas of submerged lands currently protected by sanctuary regulations should become protected by sanctuary regulations should become available for exploration and development.
Comments on "Sailboats and Drilling Rigs"
The authors' interesting review of the case history of drilling in Corpus Christi Bay contains a real message for all of us who are concerned with urban oilfield development. Our industry's situation is very aptly stated by the remark on Page 452, "we do not become concerned or involved with a problem until it faces us in a blind alley", and "when positive actions by the frequently divergent and different interests start converging, there has to be either chaos or treaty."
Intelligent and workable regulations are necessary and can be obtained through joint action by oil company personnel, representatives of the people affected and members personnel, representatives of the people affected and members of responsible governmental agencies. It is not sufficient to depend upon petroleum industry information committees and oil company public relations people to adequately inform the general public of the advantages of orderly recovery of petroleum deposits under or near urban areas.